Parallel solution-phase synthesis of 4-dialkylamino-2-methylsulfonyl-6-vinylpyrimidines.

A simple and straightforward methodology for the parallel, solution-phase synthesis of novel 4-dialkylamino-2-methylsulfonyl-6-vinylpyrimidines 9a-j has been developed. Starting from 2-methylthio-6-[2-(p-toluensulfonyloxy)ethan-1-yl]-4(3H)-pyrimidinone (6), a three-step procedure (namely, tosylate substitution by amines, base-catalyzed rearrangement, and sulfide to sulfone oxidation) using a Buchi Sincore synthesizer gave the final products in high yield after simple ethyl acetate extraction and without further purification. Interestingly, when the final oxidation step was performed on 4-arylpiperazine derivatives 8g-j, the corresponding highly polar piperazine N-oxides 9g-j were obtained, which conversely needed chromatographic purification in order to give the pure products.